Opening of epoxides with nucleophiles under acidic conditions

by James

Description: When acid is added to epoxides, nucleophiles will add to the more substituted position. The stereochemistry of the addition is trans.
Content available for Reactionguide members only. Not a member? Get access for about 30 cents / day!

yes, it is “up” in the example shown in the mechanism. The fact that OH is drawn as a “dash” implies that the methyl group is a “wedge” (up) although I was lazy and did not draw it in as such.
The reaction proceeds with inversion of configuration.

It’s a bit like an SN1, except with inversion of stereochemistry. It’s very similar to the second step in bromination or chlorination of alkenes, where the nucleophile attacks the charged 3-membered ring intermediate.